A reciprocating four-stroke straight piston is well-known in the engine arts. Referring to PRIOR ART FIG. 1, there is shown a conventional spark plug 1 that is ignited during an ignition stroke. Valve 2 is an intake valve for allowing fuel into chamber 9. Valve 3 is an exhaust valve for allowing exhaust which typically comprises some unburned fuel, carbon monoxide or other elements demonstrating some inefficiency in combustion to exit chamber 9. This inefficiency is even more pronounced in two-stroke piston engines without dedicated chambers (known two-stroke engines discussed in greater detail below). A rocker arm 4 is pivoted and valve lifter 6 raises pushrod 5 to lever rocker arm 4 to raise intake valve 2. There is typically a camshaft 7, timing belt 8 and the timing belt 8 controls the intake valve 2 lifting with the crankshaft 14 turning. A cylinder 10 is provided along with ring 11, piston 12 and connecting rod 13 to crankshaft 14 which rotates an output shaft in response to four strokes: intake, compression, ignition/combustion and exhaust, more fully shown in PRIOR ART FIG. 2.
Referring now to PRIOR ART FIG. 2, there is shown an animation sequence for a four-stroke piston of FIG. 1 having dedicated chambers 9 for each of four stokes. Beginning with Intake stroke 1, intake valve 2 is shown open in Intake stroke 1 (left) while chamber 9 is expanding to allow fuel/air to enter chamber 9. Exhaust valve 3 is closed. In Compression stroke 2 (left center), both valves 2 and 3 are closed, the chamber 9 is expanded but is beginning compression of the fuel in chamber 9 as the crankshaft 14 turns counterclockwise (arrows) prior to Ignition. In Ignition stroke 3 (right center), the spark plug 1 is ignited when the fuel/air mixture is compressed so as to cause the piston 12 to move downward from the internal combustion of the ignited mixture. The crankshaft 14 is thus forced to turn from the internal combustion. In Exhaust stroke 4, exhaust valve 3 is opened to allow the combustion results to exit as shown by the arrow above the exhaust valve 3. Chamber 9 is alternatively compressed and expanded with each of the four strokes 1, 2, 3 and 4. There thus are seen dedicated chambers 9 for each stroke of an engine cycle. When there are four “four-stroke” pistons as shown in PRIOR ART FIG. 3, there is provided a coordinated movement of crankshaft 14 as each piston is performing a different stroke of an engine cycle: from left to right, compression ready for ignition, ignition ready for exhaust, intake complete ready for compression and exhaust ready for intake.
A conventional two-stroke piston is shown in PRIOR ART FIG. 4. The upstroke is shown on the left and the downstroke is shown on the right. During upstroke (left), there is fuel compression, ignition, the transfer port is covered, the connecting rod has pushed up on the piston and the valve is open allowing fuel mixture to be drawn into the crankcase. During downstroke (right), the transfer port is uncovered and fuel mixture is forced into the chamber and burned fuel is pushed out by the compressed fuel mixture, the burned fuel shown as black dots. The piston is completely lowered and the connecting rod shows the crankshaft/connecting rod, in a down position. The output shaft is shown rotating counterclockwise.
PRIOR ART FIG. 5 shows a conventional two-stroke engine with a turbocharger having one dedicated chamber. Air enters from the left; fuel is injected by a fuel injector. A fuel and air mixture is formed in the crankcase, fills the chamber, is compressed and then is ignited by the SPARK and BURNT FUEL is exhausted toward the TURBOCHARGER where it is salvaged to provide further engine power.
The well-known Wankel rotary engine (with Otto cycle) attributed to Felix Wankel is shown in PRIOR ART FIG. 6. A shaft B is at the middle of an oblong chamber having INTAKE and EXHAUST ports. The triangular rotary piston is shown as piston A and is caused, via gearing shown, to rotate the shaft B through INTAKE, COMPRESSION, IGNITION and EXHAUST. Two spark plugs are shown at the right of the oblong chamber. It may be seen that when the piston A is causing contents of a chamber formed proximate the spark plugs to be compressed, ignition will cause combustion and the rotary piston A will rotate the shaft B.
It is generally known in the art to provide two-stroke engines as described above. A two-stroke engine may be defined as an engine having a power stroke per a revolution of an associated crankshaft of 360° and with two strokes, or, for example, upward or downward movements (upstroke/downstroke). U.S. Pat. No. 8,127,544 issued Mar. 6, 2012 to Schwiesow et al. (Schwiesow) describes the history of so-called “double acting” two-stroke engines from U.S. Pat. No. 1,785,643 to W. G. Noack et al. issued Dec. 16, 1930, to U.S. Pat. No. 7,258,086 to Fitzgerald issued Aug. 21, 2007. In Schwiesow, the following so-called “double-acting” systems are described: those of U.S. Pat. No. 2,963,008 to Waldrop, U.S. Pat. No. 4,205,528 of Grow, U.S. Pat. No. 6,199,519 to Van Blarigan, U.S. Pat. No. 6,700,229 to Sadarangani et al. and U.S. Pat. No. 7,258,086 to Fitzgerald. As early as Noack el al. '643, circa 1930, FIG. 1 shows pistons 6 and 7, and FIG. 2, shows additional compressor pistons 11 and 12 having a back and forth movement within “free piston engine” 1. Waldrop '008 shows an improvement to a free piston engine including a fuel injection system. Grow '528 adds scavenging via a “fan scavenged two-stroke cycle.”
An alleged improvement introduced by Schwiesow to these earlier “double-acting” two-stroke systems is a homogenous charge compression ignition (HCCI) for “essentially constant volume combustion.” Schwiesow, represented by Prior Art FIG. 7, depicts an embodiment in each of the '544 patent's FIGS. 8-10 wherein first and second pistons are fixedly attached to each other via a rigid connecting rod so as to oscillate in a cylindrical case from one end to the other of the cylindrical case when cycled sparked ignition of each fuel/air chamber at each end of the cylindrical case occurs.
U.S. Pat. No. 6,170,443 to Hofbauer describes a supercharged opposed piston, opposed cylinder (OPOC) internal combustion engine which may be seen in PRIOR ART FIG. 10. A crankshaft rotational axis is shown driven by pushrods and pullrods connected to eccentrics. These comprise many driving arms which make the internal operation appear similar to that of a train locomotive. The OPOC engine of the '443 patent employs a conventional exhaust system. However, U.S. Pat. No. 8,490,380, issued Jul. 23, 2013, also to Hofbauer, describes an improved OPOC system having an incoming air chamber and an exhaust chamber in communication with a combustion chamber with improved scavenging.
Also known is the so-called Bourke internal combustion engine named for its inventor, Russell Bourke (FIG. 8). The Bourke engine is described in GB514842, accepted Nov. 20, 1939. Bourke shows in his GB '842 patent, FIGS. 1-4, oppositely disposed cylinders 20 with pistons therein driving connecting rods 19 and a rotatably mounted crank shaft. “The invention consists in driving gear for internal combustion engines having opposed cylinders, pistons and piston rods, a crank shaft and transmission means for converting the reciprocating rods of the pistons into rotary motion of the crank shaft which transmission means comprises a bearing member encircling the crank pin and means connected to the pistons and engaging against opposite sides of said bearing member characterized in that said means engaging against the bearing member are formed as a pair of separate bearing blocks rigidly mounted on plate like means acting to connect said blocks together.” Bourke suggests that “each of the bearings 3, 6, 10 and 15 are preferably made up of inner and outer circular spaced races between which are a number of steel balls.”
Referring to PRIOR ART FIG. 7, the Schwiesow engine is shown in some detail. The Schwiesow engine has double-acting “Two-stroke” pistons that move from one side to the other when alternating ignition occurs.
Referring to PRIOR ART FIG. 8, the Bourke engine is shown in some detail having four “Two-stroke” pistons and may be compared to the other depicted PRIOR ART engines.
Referring to PRIOR ART FIG. 9, a pioneer so-called “one stroke” Massey-Harris gasoline engine is shown but is better described as having a rotary two stroke piston. The Massey-Harris engine is attributed to Stuart Macey and is a reciprocating rotary two-stroke piston engine (while the Shwiesow piston reciprocates back and forth from its alternating ignition at each end). A one-stroke piston may be generally defined herein as a piston having a power stroke of 180°, but we consider the Macey engine as having a rotary two-stroke piston. Consequently, the one-stroke piston, for example, may move from a top dead center to the left and stop and then to the right and stop (completing one stroke) and/or back or forward to comprise a 180° power stroke in each of the backwards or forwards direction. An example of the one-stroke internal combustion engine is Macey, U.S. Published Patent Application No. 2003/0121482, abandoned. A piston block 20 defines a combustion cavity and a compression cavity. A “working assembly 40” is rotatably disposed in the block 20 including a cylindrical portion 46, a compression paddle 50 and a piston 48. There further is depicted an arcuate combustion cavity 28 and an arcuate compression cavity 30. A drive rod 90 operably interconnects the first and second piston blocks 20 for common driving of the components of the drive block 22.
A Table is provided in PRIOR ART FIG. 11, that provides a comparison of pro's and con's of four Engines in Development. The Bourke engine has two “Two Straight Pistons” in line that reciprocate back and forth. An advantage is a low part count and a high specific power ratio. The Bourke engine has one dedicated chamber as it reciprocates through its cycles. The Schwiesow engine may be described as a double-headed piston in line and reciprocates back and forth. Schwiesow is similar in advantages to Bourke in having fewer parts and a high ratio. Schwiesow has one dedicated chamber. The Macey reciprocating rotary piston engine has similar advantages and disadvantages to the Bourke and Schwiesow engines. The recent Hofbauer engine has two opposed pistons in line. It has many parts, started with the German company Volkswagen and is well-funded. It has one dedicated chamber.
All of the above-identified patents and published applications including the Bourke patent are incorporated by reference herein as to their entire contents.
Even with the above-described improvements to two-stroke internal combustion engines and other conventional engines, there still remains a need in the art to provide further enhancements and improvements to, for example, fuel efficiency and increased power at the improved fuel efficiency and further improved scavenging by means of further embodiments of rotary and straight-line reciprocating internal combustion engines having a coordinated cycle and one-stroke, for example, a 180° power stroke.